No oil pressure on an 86 350

[lbrowne]

My gauge says 0 oil pressure. The needle doesn't move at all. I only noticed this the last couple of days when I had to start and move the truck. It doesn't move at all, it stays at it's lowest possible setting even if I rev the motor. Yes she has oil.

Pretty sure oil is getting up and around everything since she doesn't click, tick, or bang. 116k miles on the truck/motor.

She's due for an oil change which I'm going to do today hopefully. I was going to run some crankcase cleaner before I change the oil. I was going to wipe the dipstick and put it back in while it's running, at least if the oil is up the dipstick tube and up higher on the dipstick that should at least tell me the oil is getting flicked up around everything right?

Is there anything else I can check before I start droppin the pan or removing the oil sending unit or both?

Let me know.

Thanks,

lbrowne

[VileZambonie]

1st check the wire from the sending unit. Make sure it's connected good and clean. Observe the gauge, if it doesn't move ground the wire and see if the gauge moves.

[lbrowne]

Thanks - dumb question now, in what general area is the sending unit? I've only had to do one on an import before.

Down bottom towards the front of motor?

[VileZambonie]

If it's a small block chevy look towards the drivers side rear of the engine near the distributor behind the intake.

[lbrowne]

Yup, it's on a 350. I'll take a peek there.

This all makes sense since I just recently put on new valve pan gaskets, maybe I knocked it off or something.

Cheers,

lbrowne

[Lt.Del]

You can do a simple test if you wish when you change your oil.  Put a new oil filter on it.  Don't put oil into the filter when putting the new one on.  Run the truck for a few seconds.  Remove the new oil filter and see if oil is in it.  It'll tell ya if the good ole oil pumper is working.

before you condict this test though do as suggested.  Look behind and to the right (driver's side) of the distributor.  You'll see the oil sender.  

My '91 did the same thing as yours.  I found out the sender was bad.    

my '91




my '79

[lbrowne]

Ok so I checked the wire and it's connected.

I haven't tried what you said yet SgtDel, but if I start revving the truck pretty good the gauge does move, and I can get the needle to about half way across the gauge. So that's telling me the gauge works.

As soon as I let off the throttle, it goes completely back to zero right away. I'm out here in the garage right now, and I think this might be the sending unit...  what you think?

[VileZambonie]

I'd suggest you find out what your oil pressure really is http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92687
And get a new sending unit

[eventhorizon66]

You beat me to it, Vile.

[lbrowne]

Princess Auto is the equivalent to Harbor Freight here, I'll pick up one of those gauges this week.

edit: how many access point on this block do I have for this gauge? Is there one easier to get at than where the sending unit is? On my father inlaws bbl 460 he's got several spots he can use.

Thanks! lbrowne

[Lt.Del]

all that revving and the truck is still alive, well, that may be a good sign.  Does it sound like a diesel engine?   you'll know it by ear if the pump isn't working. But, do as suggested, get another sender, they are cheap.

[lbrowne]

I'll get one at my parts source place this week - I go there for everything like that.

Doesn't sound like a diesel, sounds perfectly normal. That's why I was surprised when the gauge didn't move. Something is clogged or not working somewhere so I'm going to get one of those mechanical gauges and a sending unit.

But since I got the filter and oil, I'm going to change that today. I'll let you all know when I get the sending unit this week. (that really looks like a pain to get to)

Cheers,

lbrowne

[Lt.Del]

it is a pain.  I'd get a new sender...they do go bad sometimes, then, if that doesnt solve the issue, then maybe get one of those guages to help troubleshoot, but, i think you'll see that a new sender will work.

I think you have to remove the distributor--i could be wrong.  I removed my distributor when replacing mine in the '91.  Just take the cap off and see where the rotor points to, then remove the distributor.  Put it back in the same way---hopefully the oil pump shaft and cam gears will still mesh correctly.  If not, a little jiggling and slight turns on the rotor should do the trick.  Just time it afterwards.        

I gotta tell a little story here about my first engine rebuild when i was 16 on an inline F^*D engine for my '68 mustang.  I had the block on an engine stand and when I flipped it upside down to tear down the bottom end, I heard something ping onto the garage concrete floor.  I picked it up and it was some 3 inch or so hex rod.  Didn't know what it was. So, I ignored it.

I got all new bearings, oil pump, pistons, rings, cam, crank, etc...all put in and buttoned up the top end with the head, carb, fuel pump, distributor, etc...Put the distr. on TDC and cranked her up the first time.  She started right up.  But then i started thinking...she sure did sound like a diesel engine....rattle, rattle,....that was weird.  Then I turned pale white when I realized perhaps the oil wasn't moving around. I took the oil filter off and low and behold, not a drop of oil in the filter.  

I started thinking...what makes the oil pump turn?  what is that hex recess on the bottom of the distributor shaft?.....what the heck was the 3 inch hex rod?.....it all made sense then.  I went to the coffee can of extra parts.....there always seems to be extra parts.  Found the rod.  Removed the distributor.  Placed the rod down into the oil pump and replaced the distributor.  Started it back up.  A much better sound pleasantly rang into my ears as good as listening to Beethoven.

Luckily, when i put the engine together, I coated every bearing, piston, ring and all with that thick STP oil treatment oil.  I don't even know if they make that stuff anymore. But everything was coated very well with the thick stuff which, I believe, is what saved the engine.  That little 250, bored .40 was a strong horse.  Neddless to say, I broke the engine in well that night.

[TexasRed]

I've had sending units go bad more times than ga(u)ges.

[lbrowne]

SgtDel, sounds like you really dodged a bullet on that one! Holy!

After reading some articles online, it must be my sending unit that is also leaking oil down the back of the motor as well....

Should have it this week to change out.